a. Field of the Invention
This invention relates generally to vacuum cleaners and similar apparatus for cleaning carpets and other floor surfaces, and more particularly, to a bristled roller assembly for the nozzles of such apparatus that provides reduced vibration, simplified manufacture and extended product life.
b. Related Art
For the purpose of cleaning carpets and extending carpet life, the nozzles of vacuum cleaners and other carpet cleaning apparatus commonly feature spinning bristled rollers. Typically, the bristled roller assemblies are made up of the following components: a long core axle; one or two bearings or sleeve bushings which may be installed at or near opposite ends of the axle; a geared or smooth-surfaced pulley, which may be positioned at either end of the assembly or at any point in between; a belt, which may be geared or smooth, and flat, round or v-shaped depending on the pulley type; a one-piece solid or hollow bristled roller body of plastic, wood or other material; one or more thread guard elements to reduce the accumulation of hair and other fibers which would otherwise enter and jam the bearings and/or other components of the roller assembly; and an endcap at or near each end, that support the assembly for spinning rotation relative to the fixed structure of the nozzle.
The roller assemblies may be powered by electric motors, or by air-driven impellers propelled by the airflow generated by the carpet cleaning apparatus. The shaft extensions of the motors or impellers may be smooth or may feature a geared or otherwise shaped pulley for engaging one end of a belt, the other end of which is in engagement with the nozzle's bristled roller assembly.
The above-described components are typically assembled in a generally linear arrangement, and since mass-produced components are typically less than perfect dimensionally, the linear arrangements commonly result in an imbalance of the bristled roller assembly; when the roller is spinning rapidly, this imbalance tends to generate excessive vibration, which not only renders operation unpleasant, but also may lessen the life of the roller assembly and/or the other components of the nozzle assembly such as the motor. Consequently, not unlike the need to dynamically balance newly-installed tires on automotive wheels, the roller assemblies must typically be balanced dynamically, through an expensive and arguably inconsistent worker-dependent procedure, whereby small counterweights are installed in the roller in an attempt to improve balance and lessen vibration. Typically, a bristled roller assembly is considered sufficiently balanced and its vibration acceptable for product warranty if the difference in weight between an assembly's opposite ends (the spinning weight differential) is less than one gram.
Accordingly, there exists a need for an improved roller brush assembly that incorporates the features necessary for its operation but with enhanced stability and balance characteristics that reduce or eliminate the need for a separate balancing step during manufacture. Furthermore, there exists a need for such a roller brush assembly that can be manufactured quickly and economically, and that is durable, long-lasting and generally maintenance-free during use.